Fluid-operated and electrically controlled mechanism generating an intermittent highfluid pressure in a molding machine



June 4, 1957 HEIDMANN 2,794,519

FLUID-OPERATED AND ELECTRICAL-LY CONTROLLED MECHANISM GENERATING AN INTERMITTENT HIGH FLUID PRESSURE IN A MOLDING MACHINE Filed July 9, 1956 tes FLUID-OPERATED AND ELECTRICALLY CON- TROLLED' MECHANISM GENERATING AN INTERMIT'I'ENT HIGH FLUID PRESSURE IN A MOLDING MACHINE on. 1ss--27 Unite Claims.

The present invention relates to a control mechanism for controlling the intermittent engagement of a weight with an impact tool to produce a high fluid pressure and is particularly applicable to molding machines. of the kind found in the subject matter of my co-pending application Serial No. 327,756, filed December 24, 1952.

It is an object of the invention to provide an automatic control system used with hydraulic machines operating with a moderate initial pressure and then developing a high working pressure to give the articles being molded their final shape and structure. Hydraulic machines of the above mentioned type disclosed in said application develop the high working pressure by the action of a free falling weight acting on a hydraulic system comprising an impact tool movable in a hydraulic cylinder to n produce the elastic impact giving the articles, as for example, containers, being formed their final shape and structure. The weight rebounds and at the end of its return motion is caught by a lifting mechanism which returns it to its initial starting point or level. Catching the Weight on rebound improves the efiiciency of the molding machine in that the weight need not be lifted all of the way to its initial starting point and there is an economy in the work energy expended by the machine.

In these machines the lifting movement returning the weight to the starting position must be executed only after the weight is effectively hooked and held at the uppermost point of its rebound. The invention makes it 4 possible to achieve rapid and economical operation. It also provides for automatically insuring the correct sequence of operation and full safety of operation.

The objects and advantages of the invention will be more fully understood from the following description and claims in conjunction with the accompanying drawing which diagrammatically represents a machine in accordance with the invention.

In accordance with the drawing, a weight 1 is properly positioned over an impact tool 2 hydraulically coupled to a hydraulic molding machine such as that shown in said application Serial No. 327,756. The weight 1 is slidably guided by extensions 3 slidable along columns 4 and is provided with a releasing device, as for example, hook 5 cooperating with a pivotally mounted hook 6. The latter hook is positioned to catch the weight at its uppermost travel upon rebound after having been released and dropped onto impact tool 2. A third hook or holding device 7 holds the weight in readiness for dropping in the manner described hereinafter.

Hook 7 is pivotally connected to a fixed axis 8 mounted on the machine frame or conveniently positioned on an overhead member such as a girder. Hook 6 is pivotally connected to an axis 9 on a lifting lever 19 which pivots about a fixed axis 11 mounted on the machine proper or some fixed structure. At the end opposite axis 11, lifting lever is connected to a piston rod 12 which is connected to a lifting piston 13 movable in a hydraulic cylinder 14. A compression spring 15 is positioned between the piston face opposite the piston rod and the end of cylinder 14. Fluid under pressure is supplied to the cylinder 14 by a conduit 14A, with the fluid acting on the side of the piston 13 opposite the side engaging spring 15, with the direction of flow indicated by the arrow 16. The fluid is controlled through a control mechanism 17, such as an electro-magnetically controlled valve.

In the lower position for catching the weight in the manner shown in the drawing, the lever 10 bears against an elastic stop consisting of a strong compression spring 18, the compression of which is controlled by tightening nut 19 carried by a rod 20 extending through the spring and having an abutment 20A upon which lever 1%) bears. It will be understood that spring 18 may be replaced by any type of elastic component, as for example, stacked elastic washers made of rubber or some similar resilient material or that the elastic stop may be a similar resilient device operating in similar manner to the elastic stop 18-20.

The rod 20 carries flexible electrical contacts 21 suitably arranged to close and complete, in conjunction with fixed contacts 22, a control circuit 23 receiving power from a suitable power source (not shown) connected to terminals 23B and 23C. The control circuit 23 is connected to control mechanism 17. A normally closed holding relay 24 has its coil 24A connected across the control circuit parallel with the terminal connections of electromagnetic device 17, and its mobile contact 24B opens and closes a branch line or circuit 23A which is in series with the coil of holding relay 24. Arcontrol switch 25 in series with the mobile contact 243 is positioned between the power source and the holding relay on the branch series circuit. The control switch 25 is suitably connected to a rod 25A having an abutment 25B operable by a finger or extension 10A of movable lever 10.

A finger or pusher device 26 is selectively positioned to swing hooks 6 and 7 about their axis so as to release the weightwhen desired. The device 26 is operated by the machine in the proper timed sequence or" operations.

The operation of the control system is as follows:

The weight 1 is shown in the drawing in position after engaging impact tool 2, rebounding and being caught by the hook 6. The weight tends to move lifting lever 19 clockwise, therefore, the lever bears on the elastic stop 18-20 so that mobile contacts 21 close the control circuit in the manner shown. Consequently the electromagnetic valve 17 is energized and opens, thus permitting a fiow of fluid under pressure to enter cylinder 14 on the lower side of the piston 13 so as to overcome the resistance of spring 15. In moving up, the piston 13 raises lifting lever 10 so that the weight hook 5 bears against the arcuate surface 7A of hook 7 and displaces it slightly to the right so that when the weight is lifted to its initial starting position the hook 7 swings to the left and engages hook 5 so as to retain the weight in initial starting position. The spring 18 opens the contacts 22.

Sequential to the holding relay 24 being energized and closing its contact so as to energize electro-magnetic valve 17, the piston 13 in lifting the lever It? causes finger 10A to bear against abutment 25B and thus opens the control switch 25 which opens the branch circuit 23A thus deenergizing holding relay 24 which in turn deenergizes mechanism 17. Electromagnetic valve '17 then closes and permits a backfiow of fluid from cylinder 14 through outlet 17A into reservoir 17B. Consequently the pressure drops on the lower side of piston 13 and compression spring 15 expands and overcomes the fluid pressure in the cylinder so as to force piston 13 downwardly; thereupon the lever 10 is moved clockwise and assumes again the lower position as shown bringing hook 6 in position for catching the weight upon next rebound.

The weight 1 is now releasably held by hook 7 in its uppermost position so that at the proper time in the sequence of operations finger or actuating mechanism 26 moves to the right and momentarily strikes hooks 6 and 7 and pivots or rotates them counterclockwise to the right so as to disengage the weight and allow it to fall freely under the action of gravity. The finger 25-then returns to its initial position. Once the weight falls it makes contact with impact tool 2, rebounds and is again caught by hook 6 thus tending to rotate piston lever 10 clockwise and compressing spring 18 so as to close contacts 22 and the cycle is repeated.

While a preferred embodiment of the invention has been illustrated and described, it will be understood that the invention is, in no way limited to this embodiment and that many changes may be made within the spirit and scope of the invention as defined by the following claims.

What I claim and desire to secure by Letters Patent is:

1. In a hydraulic machine having an impact tool hydraulically coupled to a specific fluid circuit of the machine and a weight selectively engagingsaid tool to create a high fluid pressure in said specific circuit, a, fluid-open ated and electrically controlled mechanism for controlling intermittent engagement between said weight and said impact tool comprising the combination of means to selectively and releasably hold said weight in spaced relationship above said impact tool and selectively release it,

guide means slidably engaging said weight so that when the weight is released gravity causes it to fall and be guided by said guide means so as to strike said'impact tool once and rebound, a pivotally mounted lifting lever, a catching device carried by said lever and having the form of a hook for catching and retaining said weight upon rebound, means for operating said lever and raising said weight to a higher level'than that at which it is caught, said last mentioned means cooperating with said means to hold the weight and to automatically transfer said weight from said catching device to said means to hold the weight when said higher level is reached, said lever operating means comprising a fiuid operated and electrically controlled mechanism.

2. A fluid operated and electrically controlled mechanism in accordance with claim 1 further including means 4 to actuate a piston having two sides and operable in a cylinder, said last mentioned means comprising a fluid circuit under pressure connected to said cylinder so that the fluid under pressure operates on one side of the piston, a compressible and extensible member on the other, connection means between said piston and said lever, and an electromagnetic fluid flow control device adapted to be opened and closed by said lifting lever.

3. A fluid operated and electrically controlled mechanism in accordance with claim 1, in which said fluid circuit includes an electro-magnetic fluid-flow control device and an electrical control circuit connected to said fluidflow control device having a power source constantly energizing it while said machineis operative, control means comprising an elastic stop cooperating with said lever and control contacts associated with said stop for opening and closing the electrical control circuit so as to selectively energize and deenergize said electro-magnetic control device so that when said weight is caught by said catching device, said electro-magnetic fluid'flow control device is energized and permits fluid to flow into the cylinder and when deenergized fluid is permitted to flow .out of the cylinder.

4. A fluidtoperated and electrically controlled mechanism in accordance with claim 1, comprising means to open and close an electrical control circuit including a first switch selectively engaged and closed by said lifting lever when the weight is caught by said catching device, a holding relay having mobile contacts and havingits coils connected across said control circuit and between said first switch and said electro-magnetic fluid flow control device, resilient means to open said switch when the lever is not in engagement with said weight.

5. A fluid operated and electrically controlled mechanism in accordance with claim 4, in which said electrical control circuit further includes a branch circuit connected between a terminal of said power source and said holding relay mobile contacts, a second switch in series with said'mobile contacts and positioned between said holding relay and said power source, means connected to said second switch engaging said lever when No references cited. 

